The invention relates to a pneumatic operating unit for compressed-air brakes.
Pneumatic operating units for compressed-air brakes, particularly of rail vehicles, are systems which are connected with their operating spaces and have the object of controlling or regulating the pressure in these operating spaces or of connecting the operating spaces with one another or of separating them from one another or of influencing the compressed-air flow by way of the connection.
For this purpose, the operating units contain valves which open and close the air paths to the operating spaces. These valves are moved by pistons which are loaded by pressures or pressure springs, so that an opening of valves will occur when the forces at the pistons are not in balance. The mentioned components are installed in housings which have connections to the operating spaces.
Particularly in the case of indirectly operating compressed-air brakes for trains, operating units with non-linear functions are known and are called control valves. They consist of a plurality of valves and pistons which influence one another and control the interaction of several operating spaces.
Since, corresponding to their object, the operating units may contain a varying number of pistons and valves in one operating unit, they differ from one another with respect to their construction. The housings of the known control valves are therefore spatial formations into which the valves, pistons, pressure springs and other components are installed from several sides.
The result is that the housings are complicated and need special castings. The valves and pistons to be installed are also special constructions with a low degree of standardization. The possibility of reacting to changing demands by means of these elements is low. Furthermore, the mounting of the known control valves requires high expenditures because a plurality of air-tight screwed and pressed connections has to be established. An additional consideration is the heavy weight and the large space requirement.
The present invention provides for a pneumatic operating unit which, because of its simple construction, on the one hand, permits a lower-cost mounting technique and, on the other hand, as a result of a modular construction, also in the case of a different volume of structural components, permits the use of as many identical or similar parts as possible.
The present invention provides for a construction in a simple axial form and without unnecessary air-tight screwed and pressed connections, which is different from the known three-dimensional formation.
According to the present invention, the pneumatic operating unit comprises a housing with at least one outer compressed-air connection device. At least one piston, piston rod, valve body and valve seat are arranged in the housing. The present invention is based on the possibility of fitting one or more cylinder bodies into the housing. The cylinder body may have different types of constructions, so that it can accommodate either a piston with the pertaining piston rod or is designed such that a valve body can be guided in it. The cylinder body may be designed such that, as a result of its shape, it directly forms a valve seat, or a valve seat may be separately inserted in it.
In order to connect the operating space or spaces in a cylinder body with the outer compressed-air connection device, one or several transverse connections from its interior to its outer surface are constructed in the cylinder body. These transverse connections are connected by way of air-carrying connections in the housing with the respective outer compressed air connection device. The connection of various transverse connections with one another by means of air-carrying connections in the housing is also conceivable.
In order to be able to construct different pressure stages in the individual operating chambers of the pneumatic operating unit, the operating unit may be designed such that the transverse connections are mutually sealed off in the axial direction. This is achieved by a surrounding sealing device at the extreme ends of the cylinder bodies, which sealing device seals off the cylinder bodies with respect to the housing.
When, in an embodiment of the present invention, the outer operating space of the outer cylinder body is to have a pressure difference with respect to the environment, here also, a sealing-off may be required with respect to the environment. This takes place by means of an end body, such as a cover plate, which is arranged on the outer face of the cylinder bodies situated at or on the housing. The end body is sealed off with respect to the outer cylinder body. In a further embodiment of the present invention, the respective outer cylinder body is sealed off in the area of the extreme axial end with respect to the housing, so that the transverse connection of the outer cylinder body is sealed off with respect to the environment. The sealing-off of the cover plate with respect to the cylinder body and the sealing-off of the cylinder body with respect to the housing can be implemented by a single surrounding sealing device.
In another embodiment of the present invention, the housing may have a rectangular cross-section. In the housing, an axial center bore is constructed into which the cylinder body or bodies is/are fitted. This embodiment is manufacturing and assembly-friendly.
According to the present invention, an arbitrary number of different or identical structural components in the form of cylinder bodies comprising a piston and a piston rod, or cylinder bodies comprising a valve can now very easily be inserted in the housing. As a result of a corresponding placing of the air connections in the housing between the outer connection devices and the transverse connections of the cylinder bodies or between various transverse connections, the operating spaces of the cylinder bodies can easily be provided with the desired compressed air.
Since, in addition, the cylinder bodies may have a similar construction despite having different functions, a cost-effective manufacturing is possible. As a result of the modular construction, the mounting of the operating units can easily be implemented and the assembly times are shortened in comparison to known constructions.
Other aspects and-novel features of the present invention will become apparent from the following detail description of the invention when considered in conjunction with the accompanying drawings.